Engine starting mechanism



June 23, 1931. w. 1 MCGRATH ENGINE STARTING MECHANISM Filed Oct. 2, 1929 2 Sheets-Sheet l www NN /N VEA/Tale Jut-1e 23, 1931. w. L. MCGRATH 1,811,401

ENGINE STARTING MECHANISM v Filed oct. 2, 192s 2 sheets-sheet 2 llllllllsr'flrnvzn [N VENTO/f Patented June 23, 1931 tengan UNITEDA STATES ,PATENT OFFICE WILLIAM L. MCGRATH, OF ELMIRA, NEW YORK, ASSIGNOR T0 ECLIPSE MACHINE COM- PANY, OF EIMIRA HEIGHTS, NEW YORK, A CORPORATION OF NEW YORK ENGINE STARTING MECEANISM Application letl'ctober 2, 1929. Serial No. 396,769.v

The present invention relates to starting mechanism and more particularly to a starter gear shift in which the meshing of the starter pinion is manually controlled, while the demeshing is automatic.

In previously known devices of the above character, it has been proposed to secure demeshing of the. pinion when the engine starts by connecting the pinion to its shaft by means of spiral splines or threads. It has further been proposed to insure proper registry of the teeth of the pinion with the tooth spaces of the flywheel by providing lost motion between the threads of the pinion and its shaft,

I and employing means for-rotating the pinion slightly on its shaft in case of tooth abutment. It has been found in practice however, that if there is lost motion between the pinion and its shaft, when the engine starts and the pinion overruns the shaft, this lost motion is taken up with a shock which may cause the breakage of the flywheel teeth at the point where demeshing occurs.

One object of the present invention is to provide a novel starter gear shift of the above type including provisions for automatically indexing the pinion to relieve abutment thereof, which embodies devices for reducing the shock attendant on the automatic demeshing of the pinion.

Another object of the invention is to provide a novel starter gear shift of the above type in which the pinion is mounted for lost motion on its shaft, said lostmotion being progressively taken up -during the meshing operation to prevent substantialback lash between the pinion and its shaft when in driving position.

Further objects and advantages will be apparent to -those skilled in this art by reference to the following description taken in connection with the accompanying drawings which show a preferred embodiment of the invention and in which:

Fig. 1 is a side'elevation of a starting'mechanism embodying the present invention, part- `ly broken away and in longitudinal section,

the parts being shown V in their normal disengaged position;

Fig. 2 is a transverse section taken substantially on the line 2 2 of Fig. l;

Fig. 3 is a detail partly in longitudinal section showing the parts when the pinion has been meshed with the flywheel gear;

Fig. 4 is a detail in perspective of the pinion in fully meshed position, partly broken away to show the threads and filled on the driving shaft; K

Fig. 5 is a view similar to Fig. 3, showing the pinion in abutting relationship with the teeth of the flywheel the pinion having been partially indexed so as to be nearly' at the point where meshing will occur;

Fig. 6 is a vertical section taken substantially on the line 6 6 of Fig. 5, and

Fig. 7 is a perspective detail of the end of the driving shaft with the fillets and retaining ring removed therefrom, indicating their proper relative positions. i

Referring first to Fig. l of the drawings, a starting motor 10 is shown having a power member in the form of an armature shaft 11 which is extended and provided with spiral splines or threads preferably four in number as indicated at 12. The outer lend of the shaft 11 is mounted in a suitable bearing 13 in an outboard housing 14 attached to the motor casing. This extension 14 is provided 'with a suitable iange 15 for attachment to the flywheel casing of an engine to be started, the parts being so dimensioned that the iiywhee'l 16 of the engine is properly located adjacent to the drive end of the shaft 11.

A starter pinion 17 is loosely threaded on the shaft 11, having internal spiral splines or threads 18 which are adapted to cooperate with the threads 12 on shaft 11 but which do not fill the spaces between the threads 12 so that spaces 19l (Fig. 2) are left, which allow a limited relative rotation between the shaft and pinion for purposes of indexing.

Pinion 17 is provided with a rearwardly extending cylindrical sleeve 2O rigidly fixed thereto as indicated at 21, said sleeve being spaced from the shaft 11 so as to receive a control nut 22 which is slidably mounted therein. The control nut is connected to rotate with sleeve 2O by suitable means such as oppositely extending ears 23 which are adapted to slide freely within axially extending slots 24 of the sleeve 20. The nut 22 is also provided with internal threads 25 which are adapted to cooperate with the threads 12 of shaft 11 and when in the position shown in Fig. 3 virtually fill the spaces therebetween so that the nut is then threaded on the shaft 11 without rotary lost motion. A spring 26 is mounted within the sleeve 20 bearing at one end against the end of pinion 17 and at the other end against the nut 22, thus yieldably maintaining the nut and .pinion axially separated, this axial separation being limited by the engagement of the threads 25 of the nut against the driving sides of threads 12 and the engagement of threads 18 of the pinion against the non-driving sides of threads 12.

A shifter sleeve 27 is loosely journaled upon the shaft 11 adjacent to the nut 22, and is provided with a cylindrical portion 28 adapted to engage said nut and move it longitudinally in a direction toward the flywheel 16. The shifter sleeve is also provided with anouter Vcylindrical portion 29 having an opening in one side thereof defined by a shoulder 30 and a curved edge 31 leading to an apex 32 to the rear of said shoulder 30. n A manually operable shift lever 33 is pivoted at 34 in any suitable manner onthe outboard housing 14 and is provided with a lug 35 at its lower end adapted to engage in the opening of the shifter sleeve 27 and normally rest in the apex 32 of said opening. A washer 36 is adapted to be retained on the the cylindrical portion 28 of the shifter sleeve as by means of an outwardly flanged portion 37 thereof and is normally pressed against such retaining means by a suitable coil spring 38.'

' According to the present invention, a means is provided for taking up the rotary lost motion between `the pinion 17 and shaft' 11 when the pinion is in meshing engagement with the flywheel 16. This means, as illustrated, is in the form of a pair of fillets 40 which are adapted to be rigidly mounted on shaft 11 against the non-driving sides of a pair of threads 12 adjacent the meshing position of4 pinion 7. The fillets are formed with feet adaptedv to fill cut-out spaces 41 of threads 12 and to merge into the surfaces of the threads, and are provided, at their other ends with T shaped heads, the arms 42 of which are adapted to liein cut-out nemesi. l

at their opposite ends to extend substantially parallel with the threads, leaving spaces 45 of sufficient width to receive the threads 18 of pinion 17 without substantial back-lash. The fillets are retained in operative position on the shaft 11 by suitable means such as a retaining ring 46 adapted to fit closely over the fillets and the threads 12, having inturned lugs 47 adapted to fit in the spaces 45, and lugs 48 adapted to fit in the spaces 45' between the threads 12 which are not provided with fillets. The retaining ring 46 is further provided with a pair of lugs 49 on the outer face thereof which are adapted to be turned down into the spaces between threads 12 behind the arms 42 of the fillets to lock the parts in assembled position. The retaining ring also serves as a stop for the pinion 17.

In operation, starting with the parts in the position shown in Fig. 1, when the'lever 33 is swung by the operator in a counterclockwise direction, the pin 35 thereon engages the shoulder 30 of shifter sleeve 27, moving said sleeve to the right and causing the cylindrical thrust portion 28 thereof to engage the nut 22 and move the nut and pinion assembly toward the flywheel 16. In case the pinion teeth are in proper registry with the tooth spaces of the flywheel, the pinion moves into mesh, the threads 18 thereof riding up the curved Sides 44 of the fillets intov the spaces 45. During this meshing action the pinion moves forward without rotation due to its engagement with the teeth ofthe stationary flywheel. The control nut 22 is also prevented from rotation due to its splined `connection with the pinion. The armature shaft 11 is therefore caused to rotate forward slightly due to its spiral connection with the control nut which is carried forward longitudinally by the action of the shift lever 33 as described until the assembly reaches the position shown in Fig. 3. The lever 33 thereupon closes the switch 39 thus energizing the motor 10. The consequent rotation of shaft 11 moves the pinion 17 into fully meshed position as shown in Fig. 4 by reason of the angularity of threads 12, and thereupon rotates the pinion to crank the eng1In case the pinion and' flywheel teeth should abut, longitudinal movement of the pinion is arrested but continued pressure on the shifter sleeve 27 'causes the nut 22 to slide within the sleeve 20 toward pinion 17 as illustrated in Fig. 5. This causes the pinion to be rotated on the driving shaft by reason of the splined connection between the pinion and control nut while the pinion is pressed against the flywheel by spring 26 as shown in Fig. 6. When proper registry is thus secured the pinion 17 advances into mesh with the iiywheel and cranking occurs as above described.

When the en inestarts under its own power, the pinion 1 overruns the shaft 11 and is automatically demeshed from the iywheel by the action of the inclined surfaces on the pinion and shaft. Inasmuch as the fillets 40 prevent any substantial amount of backlash between the pinion 17 `and shaft 11 when the pinion is in fully meshed position, the reversal of direction of the drive t0 the pinion takes place without any severe shock to the parts, and the curved contours 44 of the fillets cause an easy and rapid traversal of the pinion to its idle position.

This demeshing action is not interfered with by the manual meshing means since the initial rotation of the motor shaft, aided by the `frictionalengagement of the washer 36 with the end of the pinion sleeve 20, rotates the shifter sleeve 27 to carry the shoulder 30 out of the path of the shifter 35. The shifter sleeve 27'is therefore moved back to its idle position by the spring 38 even though the operator maintains the lever 33 in starting p0- sition. When the operator releases the lever 33,l the lug 35 thereon engages the curved surface 31 of the opening in sleeve 27, thus rotating the sleeve back to its original position with the lug 35 engaged in the apex 32 of said opening.

The pinion 17 is preferably maintainedin its idle position by some form of antidrift means. As illustrated, this function is accomplished by relieving the driving sides of threads 12 adjacent the idle position of nut 22 as shown at 12. This allows the spring 26 to slide the nut 22 slightly further from the pinion 17 than its relative position where the threads 12 maintain a constant angle, and in consequence makes it necessary to move the nut toward the pinion against the action of spring 26 in order to move the nut .along the shaft on to the constant angle portion of the threads. Since the angle of the surfaces 12 with the axis of the shaft is obviously smaller than the angle of repose, it will be readily appreciated that any forces applied to the pinion are incapable of moving the nut 22 toward the pinion against the pressure of spring 26, so that when the nut is in engagement with the surfaces 12', the pinion assembly is effectively locked against drifting or rebounding.

Although but one embodiment of the invention has been shown in detail, various other embodiments will now suggest themselves to those skilled in the art and various changes may be made in the construction., proportions. and arrangement of parts withgage and drive a member of an engine to be started, means under the control of the operator for moving the driving member into driving position, means for automatically l moving said driving member to idle position when the engine starts and means for restricting the rotary lost motion of the driving member on the power member when in driving position.

2. fn a device of the class described, a ower member, a driving member mounted or longitudinal movement and limited rotary movement thereon and adapted to engage and drive a member of an engine to be started, means under the control of the operator for moving the driving member into driving position, means for automatically moving said driving member to idle position when the engine starts and means for progressively restricting the freedom 'of the driving member on the power member as it approaches driving position.

3. In a device of the class described, a power member, a driving member mounted for longitudinal movement and limited rotary movement thereon and ada ted to engage and drive a member of an engine to be started, means under the control of the operator for moving the driving member into driving position, means for automatically moving said driving member to idle position when the engine starts and means for progressively restrict-ing the freedom of the driving member on the power member as it approaches driving position, said last named means beingv formed to cooperate with the driving member to move it away from driving engagement when the engine starts.

4. ln a starting mechanism for internal combustion engines a power shaft, a toothed driving member mounted for longitudinal movement and limited rotary lost motion thereon and adapted to engage and drive a toothed member of an engine to be started, means under the control of the operator for moving the driving member into driving position, means operating in case of tooth abutment of the members to rotate the engine driving member relative to its shaft to relieve said abutment and means to prevent rotation of the driving member relative to its shaft when in driving position.

5. ln a starting mechanism for internal combustion engines a power shaft, a toothed driving member/mounted for longitudinal movement and limited rotary movement thereon and adapted. to 'engage and drive a toothed member of an engine to'be started,

means under the control of the operator formoving the driving member into drivingl position, means operating in case of tooth abutment of the members to rotate the driv-` ing member on its shaftto relieve said abutment and means to progressively restrict rotation of the driving member on its shaft as it moves into .engagement with the engine member.

6. In a starting mechanism for internal combustion engines a power shaft, a toothed driving member' mounted for longitudinal movement and limited rotary movement thereon and adapted to engage and drive a toothed member of an engine to be started, means under the control of the operator for moving the driving member into driving position, means operating in case of 'tooth abutment of the members to rotate the driving member on its shaft to relieve said. abutment, means for automatically moving the driving member back to idle position when the engine starts and means to progressively restrict rotation of the driving member on its shaft so it moves into engagement with the engine member, said last means being arranged to initiate the movement of the driving member back to idle position. K

7. In a starting mechanism, a drive shaft, a pinion having a lost motion threaded connection th-erewith, means for moving the pin ion along the shaft into mesh with a memi'* ber of-an engine to be started and means on said shaft for gradually taking up the lost motion between the pinion and shaft as the pinion moves into fully meshed position.

8. In a starting mechanism, a drive shaft, a pinion having a lost motion threaded connection therewith, means for moving the pinion along the shaft into mesh with a member of an engine toibe started and a fillet mounted on said shaft and adapted to. gradually take 11p-the lost motion between the pinl ion and shaft as the pinion moves into meshing position.

9. In a starting mechanism, a drive shaft, a pinion having a lost motion threaded connection therewith, means for movingthe pinion along the shaft into mesh with a member of an engine to be started and a fillet fixed on said shaft near the driving endof the threads thereof and of such cross sec.

tion at said end as to take up the'lost motion between the threads of the pinion and shaft.

10. In a starting mechanism, a drive shaft, a pinion having a lost motion threaded connection therewith, means for moving the pinion along the shaft into mes'hwith a member of an engine to-be started and a llet fixed on said shaft near the driving endof the threads thereof and of such cross section at said end as to take up theplost m0- I -have signed this n izo 

